1. Field of the Invention
The present invention relates to a mechanism for locking a switch in a screw tightener in an operative state so as to maintain operation of the screw tightener, or in an inoperative state so as to prevent operation of said screw tightener.
2. Description of the Related Art
Screw tighteners are used for tightening screws normally by pulling triggers to activate motors for rotating driver bits. It is however preferred that the trigger be designed to lock in an inoperative position so that the trigger cannot be carelessly pulled to thereby preventing any possible malfunction. Moreover, it is also preferred to be able to lock the trigger in an operative position so as to be able to tighten screws while the driver bit is kept rotating when the screw-tightening operation is continuously performed.
In order to meet the above-mentioned needs, there has heretofore been proposed and adopted locking mechanisms capable of either for restraining a trigger from being pulled or preventing the operation of a motor from being suspended.
However, locking mechanisms which function in both ways have been non-existent.